Recently, a radial ply carcass has been used for motorcycle tires. Such a motorcycle radial tire has been made based on technique for four-wheeled vehicle tires, e.g. passenger car tires. That is, the tire has been provided with a belt reinforcement formed as follows: a rubberized fabric (d) is cut bias at a small angle (alpha) to the cord direction as shown in FIG. 7, which is usually 15 to 30 degrees; and the cut fabric (e) is wound around a carcass with connecting the ends (f) as shown In FIG. 6 to form an annular belt reinforcement (a), and accordingly the laid angle of the belt cords (b) to the tire equator becomes the same bias angle (alpha).
In such a bias belt structure, however, steering stability during straight running and cornering, especially at high speed, is not good.
On the other hand, Japanese Utility-Model Publication No.58-160805 discloses a belt making method, in which a belt cord is wound spirally around the radial carcass and continuously across the tread width at small angles to the circumferential direction of the tire to form a jointless belt. When this is used in the motorcycle tire instead of the conventional belt, steering stability during high speed straight running is improved, but the stability during cornering is not improved contrary to expectation. Further deterioration of tire durability has sometimes been observed.
Thus, it is difficult to satisfy the requirements for cornering and the requirements for straight running at the same time because of the cornering mechanism of the motorcycles which is greatly different from that of the four-wheeled vehicles. That is, the motorcycle is inclined greatly during cornering and accordingly the ground contacting region moves greatly.